The present invention relates to a ramp motion mechanism used to load and unload a read-write head to and from a surface of a data storage medium.
Data storage is an important aspect of today""s information technology. Great efforts have been made by the storage industry to increase the areal data density of a storage medium in order to meet the ever increasing demand for higher capacity storage devices. Various types of disks, including magnetic disks and optical disks, constitute recording media.
Magnetic storage devices such as fixed or removable magnetic disks and tapes are widely-used conventional storage devices. The state-of-art conventional magnetic hard drive systems can achieve extremely high linear bit densities, especially with the new MR and GMR magnetic heads. For example, the areal density of many hard disk drives is on the order of about one gigabits per square inch.
Optical storage devices are emerging as an alternative technology to the conventional magnetic technology because of their potential for high density data storage. The areal density of an optical storage device, in principle, is only limited by the diffraction limit of an illuminating optical beam for reading or writing. One type of commercial optical storage technology is based on magneto-optical materials. These materials can currently produce an areal data density of about one gigabits per square inch.
Generally, each data storage device includes a spindle motor for rotating one or more disks containing data, a head assembly for recording data onto and reproducing data from the disks, and an actuator for moving the head assembly. The actuator typically includes an electromagnetic coil motor, usually a voice coil motor, to move the actuator with the head assembly back and forth over a disk surface.
Data is generally stored in each disk in a series of concentric or spiral tracks. These tracks are accessed by one or more read/write heads in the head assembly. A head is mounted to an arm that is in turn mounted to the voice coil motor. During operation, it is necessary to move the head from a current position to a target track in an operation referred to as a xe2x80x9cseekxe2x80x9d operation. In such a seek operation, a command is provided to the data storage device to access a certain sector on the disk(s). If the head is not positioned over a target track containing the desired sector, a seek profile is determined. The seek profile contains various parameters associated with the head, including acceleration, deceleration, velocity and position information of the head. The seek profile is used to move the head from its current position to the target track by controlling the voice coil motor to move the head to the target track. Periodically, the actual position and velocity of the head are compared to the seek profile and adjustments are made by controlling the voice coil motor.
Once the head is positioned over the target track, the head is maintained over the target track""s center line for accurate read/write operations in an operation known as track following. A position error signal (PES) is generated based on variations of the head from the center line of the target track. The PES is part of a closed-loop servo drive system which obtains actual head position information based on a servo pattern and compares the servo pattern to the desired head position information. When the PES identifies a variation, the servo control system provides correctional commands to the voice coil motor to accurately maintain the head over the center line of the target track.
In order to achieve improved mechanical stability and to reduce noise in positioning the head assembly, disk drives also typically employ an actuator mechanism to position the read/write head over the recording surface of the disk.
An actuator assembly designed for a disk contained in a removable shuttle or cartridge must be able to move the read/write head away from the recording disk into a xe2x80x9cpark positionxe2x80x9d in order to prevent damages to the head when the disk shuttle/cartridge is either inserted or removed from the drive. Similarly, the actuator assembly also needs to move the read/write head toward the surface of the recording disk into a work position., These are relatively large movements for the read/write head, and a ramped surface is needed to provide highly repeatable loading and unloading movements of the read/write head to maximize usable disk space.
Therefore, there is a need for an invention to provide a highly repeatable loading surface for loading and unloading a read/write head to and away from a surface of a recording medium.
Advantages of the invention include one or more of the following. The invention provides a simple, low-cost and reliable system for loading and unloading the read-write head to and from the media inside a shuttle. One advantage is that the invention provides a highly repeatable loading/unloading surface for the read-write head. Another advantage of this device is the provision of reliable positioning and smooth transition of the head to and from the media, thus protecting the data stored in the media.
Because the design of this invention is simple, the aforementioned advantages are achieved without increasing the complexity of the drive, thereby increasing the performance and reliability of the entire disk drive system.
In general, in one aspect, the invention features a ramp motion mechanism for loading and unloading a read/write head positioned at an end of an actuator arm in a disk drive, wherein said read/write head accesses and records information upon a disk residing inside a shuttle removable from the disk drive. The ramp motion mechanism consists of a base fixedly mounted in the disk drive, and a nose slidably mounted on the base, the nose has a ramped surface, the surfaces guide the read/write head toward and away from a surface of the disk.
Implementation of the invention may include one or more of the following features. The base may have a protrusion adapted to engage a notch in the nose to lock the nose in an extended position. The base further may be affixed to a lever mounted on a base plate of the disk drive to lock the nose in a retracted position. A plurality of positional and angular orientations may be controlled by applying a force on the nose. They may have angular orientations with six degrees of positional and angular freedom in three dimensions. The force may be applied to a particular area on the nose resulting in a reaction force to the force located at a plurality of pads on the nose.
In another aspect, the invention is directed to a method for loading and unloading a read/write head to and from an edge of a disk surface. The method includes one or more of the following. Moving a ramped surface of a fork of a ramp motion mechanism movably affixed to a static base of the mechanism toward the edge of the disk surface to receive the read/write head. It engages a lifter attached to the read/write head to slide along the ramped surface, and it moves the ramped surface away from the edge of the disk to remove the read/write head away from the surface of the disk.
The method may control the fork in a plurality of angular and positional orientations by applying a force to the fork and obtaining a reaction force from a plurality of pads on the fork. The fork may have at least two fixed positions on the base. The base and the fork may be formed of plastic.
In yet another aspect, the invention is directed to a device for loading and unloading a read/write head to and from an edge of a disk surface. The device having a static ramp and a ramp nose, the ramp nose sliding in a channel formed on a top surface of the static ramp to provide precise, repeatable pathway for loading and unloading the read/write head.
In another aspect, the invention is directed to a method for loading and unloading a read/write head to and from an edge of a disk mounted in a disk drive. The method providing a ramp motion device including a static ramp and a ramp nose sliding in a channel formed on a top surface of the static ramp. The ramp nose providing a pathway for loading and unloading the read/write head, and controlling the ramp nose in angular and positional orientations by applying a force to the ramp nose. The ramp nose may have a plurality of pads which supplies a reaction force in response to the applied force. The method may provide a lever affixed to a base plate of the disk drive, and may apply the force to the ramp nose.
In another aspect, the invention is directed to a ramp motion device for loading a read/write head, having a movable nose adapted to engage the read/write head, a support base whereupon the movable nose moves between two positions in a channel on the support base to move toward and away from a surface of a disk, and a plate lever, fixedly mounted on a base plate of a disk drive and attached to the support base at a first end, to place the movable nose in the two positions. The nose and the support base may be plastic. The second end of the plate lever may be attached to a spring. The lever may be metallic. The read/write head may be attached to the distal end of an arm of an actuator of the disk drive.